Files
ai-for-dummies/.agents/skills/motion/SKILL.md
T
Marcos Paulo 79920c9e6c
verify-and-publish / gate (push) Successful in 7m4s
verify-and-publish / publish (push) Has been skipped
feat: give the chapters motion, diagrams, and retrieval practice
Three strands of work on the chapter surface, all reading from the same
constraint: this site ships no runtime dependencies, so every effect below
is native CSS or an .astro component.

Motion (src/styles/motion.css, DrawRule.astro). A scroll-driven layer of
reveals, hero parallax, section depth, and a hairline that paints itself
along its path, scrubbed by `animation-timeline: view()` — 0KB against
lottie-web's ~60KB gzipped on the main thread. Every scrubbed rule sits
inside `prefers-reduced-motion: no-preference` and `@supports`, so a
Firefox reader or an opted-out one gets the complete static page rather
than one with holes in it. Ranges key to `cover 40%`-`cover 75%` where the
motion is meant to be watched: `view()` ranges key to first visibility,
which on a 2600px page is long before anyone is reading the section.
`.agents/skills/motion/references/scroll-driven.md` records the technique
and the two ways `pathLength` normalisation was broken while building it.

Diagrams (StepFlow.astro, WorktreeMap.astro). The `.steps` stack on
/skills/, /models/, and /agents/ becomes a numbered flow with connectors,
and /agents/ grows the worktree map it was describing in prose — reusing
the `trees` collection rather than a second set of strings. The map's
static variant is gated one class deeper than full-guide's page styles, so
the interactive copy renders byte-identical. Connectors are pseudo-elements,
not SVG: a stretched path desynchronises its own dash pattern, and a
straight line does not need one. Mermaid was considered and rejected at
~1MB of runtime.

Retrieval practice (/rules/, /skills/). A "check yourself" section of
native `<details>` question/answer pairs plus a citation row, both bilingual
through the existing `data-copy` toggle, and both JavaScript-free.

Two audit blind spots surfaced and are closed rather than worked around:
`build.inlineStylesheets: 'never'`, because Astro inlined sheets under ~4kB
and audit-ui.mjs reads its colour and size baseline from dist/_astro/*.css;
and `--columns` declared in the grid components, because an element-level
custom property is not a declaration the audit can resolve.

legacy/styles/skills.css is renamed and imported for its side effect. Inside
a *page*, `?url` resolves to that page's own CSS chunk whatever file it
names, so the link pointed at the wrong asset and the sheet was emitted but
never loaded — the package preview had been rendering unstyled and
overflowing since the Astro cutover.

verify.mjs gains 5 assertions for the recall sections and their Portuguese
copy: 89 now, against the 84 baseline.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-09-06 16:04:08 -03:00

2.7 KiB
Raw Blame History

name, description
name description
motion Add or review animation on the ai-for-dummies site — transitions, state changes, view transitions. Use when any element moves, fades, or transforms, or when auditing existing motion for performance and reduced-motion support.

Motion

This is an editorial-print design. Motion is punctuation. Read ../../rules/animation.md — it is binding; this is the procedure.

Decide it should move

Answer out loud: what does this motion tell the user that the static state does not? Valid answers: something changed, attention needs directing to what changed, a layout shift needs smoothing. "It feels more polished" is not an answer — on this design it reads as generic.

If there is no answer, ship it static. That is a legitimate, common outcome.

Build it

.panel {
  transition:
    opacity 180ms cubic-bezier(0.2, 0, 0, 1),
    transform 180ms cubic-bezier(0.2, 0, 0, 1);
}
.panel[data-state='entering'] {
  opacity: 0;
  transform: translateY(6px);
}
  • transform and opacity only. Animating width/height/top/left forces layout every frame and shows up as a failed INP (budget: 200ms).
  • 150250ms for UI feedback; up to 400ms for a page transition.
  • One thing moves at a time. No staggered card cascades.
  • will-change only immediately before animating, removed after.
  • No animation library. This site's thesis is having no runtime dependencies.
  • Scroll-scrubbed motion (reveals, parallax, depth, line draw) has its own rules — ranges, feature gates, the linear exception, SVG line drawing. Read references/scroll-driven.md before touching src/styles/motion.css.

Reduced motion is not optional

@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

Then test it: DevTools → Rendering → Emulate prefers-reduced-motion: reduce. The end state must still be correct and the UI still usable. Reduced, not broken.

Page transitions

Astro's <ClientRouter /> is the only sanctioned motion dependency. Before enabling it, verify:

  • JS disabled → full navigation still works
  • browser back/forward still works
  • the review desk's query-param deep links survive
  • prefers-reduced-motion is honoured

Audit an existing animation

grep -rn "transition\|animation\|@keyframes\|transform" src/ --include="*.astro" --include="*.css"

For each hit ask: does it animate a layout property? does it respect reduced motion? is there a stated purpose? Three questions, three possible fixes.